VulnerabilityPublished 13 May 2026

CVE-2026-44295: protobufjs protobuf.js · Code Injection

Affects protobufjs protobuf.jsSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 2.0.2 or 1.2.1 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

8.7High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.0.2, 1.2.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Changed
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade protobuf.js to 2.0.2 or 1.2.1; protobufjs-cli to 1.2.1.

Affected software

Product	Affected	Fixed in
protobufjsprotobuf.js	Affected >=2.0.0 <2.0.2	Fixed in 2.0.2
protobufjsprotobuf.js	Affected <1.2.1	Fixed in 1.2.1
npmprotobufjs-cli`pkg:npm/protobufjs-cli`Other threats	Affected <1.2.1	Fixed in 1.2.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in protobuf.js versions 1.2.1 and 2.0.2. Users should upgrade to at least these versions to remediate the issue. No additional mitigations are specified.

Description

CVE-2026-44295 is a high-severity vulnerability in protobufjs-cli, the command line add-on for protobuf.js. Before versions 1.2.1 and 2.0.2, the static code generation feature (pbjs) could produce unsafe JavaScript identifiers derived from schema-controlled names without proper sanitization. This flaw allows crafted schemas or JSON descriptors to inject unsafe code into the generated JavaScript output. The vulnerability is classified as CWE-94 (Improper Control of Generation of Code). It has a CVSS v3.

Impact

Successful exploitation can lead to code injection in the generated JavaScript output, potentially allowing an attacker to execute arbitrary code within the context of the application using protobuf.js. This impacts confidentiality and integrity of the affected system. There are no known exploits in the wild at this time.

Summary

The vulnerability in protobufjs-cli's static code generation (pbjs) arises from insufficient sanitization of namespace, enum, service, or derived full names when generating static JavaScript code from schemas or JSON descriptors. This can lead to code injection (CWE-94), where unsafe JavaScript identifiers are emitted based on attacker-controlled input. Versions prior to 1.2.1 and 2.0.2 are affected. The vulnerability allows an attacker with limited privileges (PR:L) and requiring user interaction (UI:R) to execute injected code, impacting confidentiality and integrity. The vulnerability is fixed in protobuf.js versions 1.2.1 and 2.0.2.

CWE-94Improper Control of Generation of Code (Code Injection) (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #10OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Architecture and Design · Refactoring
Refactor your program so that you do not have to dynamically generate code.
Architecture and Design
Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V5.2.8 (opens in a new tab)
V5.2.5 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
Leverage Executable Code in Non-Executable Files (opens in a new tab)
Manipulating User-Controlled Variables (opens in a new tab)
Code Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/protobufjs/protobuf.js/security/advisories/GHSA-6r35-46g8-jcw9 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 May 2026, 19:12 UTC

WeaknessesCWE-94

Technical details

References

Community reviews

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